REPTILES 



435 



Vertebrata. — The Fishes are still of Carboniferous types, and 

 many of the same genera occur, while new ones are brought in. 

 To the Sharks are added the curious Menaspis, which is armed 

 with numerous long and curved spines. Among the Dipnoi the 

 genus Ceratodus, very closely allied to the modern lung fish of 

 Australia, makes its first appearance. 



The Amphibia are represented, as in the Carboniferous, by the 

 Stegocephala, and several of the older genera persist, but many 

 new forms appear for the first time, several of which much surpass 

 the Carboniferous genera in size. 



The most important character that distinguishes the life of the 

 Permian from that of all preceding periods is the appearance in 

 large numbers of true Reptiles. There is no reason to suppose 



Fig. 146. — Permian Stegocephalan, Eryops megacephalus, 1/7. 

 the side. (Cope.) 



Skull seen from 



that such a variegated reptilian fauna can have come into exist- 

 ence suddenly, and their ancestors will doubtless be discovered in 

 the Carboniferous ; but while no true reptiles are certainly known 

 from the latter, in the Permian they are the most conspicuous ele- 

 ments of vertebrate life. These reptiles represent two orders, one of 

 which, the Proganosaurid, is a very central group, from which many 

 other reptilian orders appear to be descended ; Proterosaurus and 

 Palceohatteria are the most important Permian genera of this group. 

 The second order, that of the Theromorpha, is remarkable for its 

 many approximations to the structure of the mammals, as well as 

 for the curious and bizarre forms which many of its members 

 assume. This is the only order of reptiles which has so far been 

 found in the Permian of Texas, but of this group no less than 15 



